The invention relates generally to a membrane structure. More particularly, the invention relates to a membrane structure having high flux and high selectivity. The invention also relates to a method of making a membrane structure.
Porous membrane structures have been extensively used in filtration, separation, catalysis, detection, and sensor applications. Creating membrane structures having fine pores and high flux is difficult, as the flux through the membrane decreases with decreasing pore size, a relationship that urges the use of layers that are as thin as practicable. Fabricating thin porous layers with uniform pores over large surface area and that are mechanically robust is a challenging task. Therefore, thin, fine porous membranes typically are stacked on thicker substrates with coarser pores. In such membrane structures it is extremely difficult to control the layer thickness of the fine pore layer to within a few microns. In spite of much effort, the currently available membrane structures with fine pores exhibit undesirably low permeance. Therefore, it is desirable to improve the efficiency of fine porous membrane structures suitable for high temperature, high pressure, and/or corrosive atmospheres and to develop suitable methods to fabricate such structures.